I am using a VPS with 2 GB of RAM on a 1 core CPU. (Ubuntu 20.04 + nginx1.21.6 + php7.4 + Mariadb10.5)
And run 3 WordPress websites, and the average number of concurrent users is around 10.
But I recently saw the following error in the log of PHP-FPM.
[pool www] server reached pm.max_children setting (20), consider raising it
And I thought there was something wrong with the server, so I checked several parts.
Because I don't think there's any reason to get a max_children error with this number of visitors.
But no matter how much I check, I don't know why Php-fpm creates so many processors.
Here's the memory usage I checked with ps_mem:
1.1 MiB + 145.5 KiB = 1.2 MiB dbus-daemon
812.0 KiB + 488.5 KiB = 1.3 MiB udisksd
1.2 MiB + 110.5 KiB = 1.3 MiB htop
1.2 MiB + 138.0 KiB = 1.3 MiB sftp-server (2)
2.4 MiB + 82.5 KiB = 2.5 MiB bash
3.5 MiB + 786.5 KiB = 4.2 MiB systemd (3)
4.9 MiB + 1.4 MiB = 6.3 MiB sshd (4)
13.3 MiB + 369.5 KiB = 13.6 MiB multipathd
14.7 MiB + 3.0 MiB = 17.7 MiB systemd-journald
31.1 MiB + 5.8 MiB = 36.9 MiB nginx (3)
40.3 MiB + 39.5 KiB = 40.3 MiB redis-server
65.0 MiB + 1.2 MiB = 66.2 MiB fwupd
189.6 MiB + 181.5 KiB = 189.7 MiB mariadbd
639.8 MiB + 276.8 MiB = 916.5 MiB php-fpm7.4 (21)
I also checked the access logs, but only a handful of visitors and bots were logged.
the main settings of my web server are as follows.
Timeout config
Nginx
client_body_timeout 14;
client_header_timeout 14;
keepalive_timeout 25;
send_timeout 13;
Server block
fastcgi_read_timeout 30;
php
max_execution_time = 30
In www.conf
pm.max_children = 20
pm.start_servers = 5
pm.min_spare_servers = 5
pm.max_spare_servers = 15
In php.ini
[PHP]
engine = On
short_open_tag = Off
precision = 14
output_buffering = 4096
zlib.output_compression = Off
implicit_flush = Off
zend.enable_gc = On
zend.exception_ignore_args = On
expose_php = Off
max_execution_time = 30
max_input_time = 60
max_input_vars = 2000
memory_limit = 128M
error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT
display_errors = Off
display_startup_errors = Off
log_errors = On
log_errors_max_len = 1024
ignore_repeated_errors = Off
ignore_repeated_source = Off
report_memleaks = On
variables_order = "GPCS"
request_order = "GP"
register_argc_argv = Off
auto_globals_jit = On
post_max_size = 65M
auto_prepend_file =
auto_append_file =
default_mimetype = "text/html"
default_charset = "UTF-8"
doc_root =
user_dir =
enable_dl = Off
file_uploads = On
upload_max_filesize = 64M
max_file_uploads = 20
allow_url_fopen = On
allow_url_include = Off
default_socket_timeout = 60
[CLI Server]
cli_server.color = On
[Pdo_mysql]
pdo_mysql.default_socket=
[Phar]
[mail function]
SMTP = localhost
smtp_port = 25
mail.add_x_header = Off
[ODBC]
odbc.allow_persistent = On
odbc.check_persistent = On
odbc.max_persistent = -1
odbc.max_links = -1
odbc.defaultlrl = 4096
odbc.defaultbinmode = 1
[MySQLi]
mysqli.max_persistent = -1
mysqli.allow_persistent = On
mysqli.max_links = -1
mysqli.default_port = 3306
mysqli.default_socket =
mysqli.default_host =
mysqli.default_user =
mysqli.default_pw =
mysqli.reconnect = Off
[mysqlnd]
mysqlnd.collect_statistics = On
mysqlnd.collect_memory_statistics = Off
[OCI8]
[PostgreSQL]
pgsql.allow_persistent = On
pgsql.auto_reset_persistent = Off
pgsql.max_persistent = -1
pgsql.max_links = -1
pgsql.ignore_notice = 0
pgsql.log_notice = 0
[bcmath]
bcmath.scale = 0
[browscap]
[Session]
session.save_handler = files
session.use_strict_mode = 0
session.use_cookies = 1
session.use_only_cookies = 1
session.name = PHPSESSID
session.auto_start = 0
session.cookie_lifetime = 0
session.cookie_path = /
session.cookie_domain =
session.cookie_httponly =
session.cookie_samesite =
session.serialize_handler = php
session.gc_probability = 0
session.gc_divisor = 1000
session.gc_maxlifetime = 1440
session.referer_check =
session.cache_limiter = nocache
session.cache_expire = 180
session.use_trans_sid = 0
session.sid_length = 26
session.trans_sid_tags = "a=href,area=href,frame=src,form="
session.sid_bits_per_character = 5
[Assertion]
zend.assertions = -1
[Tidy]
tidy.clean_output = Off
[soap]
soap.wsdl_cache_enabled=1
soap.wsdl_cache_dir="/tmp"
soap.wsdl_cache_ttl=86400
soap.wsdl_cache_limit = 5
[sysvshm]
[ldap]
ldap.max_links = -1
[dba]
[opcache]
opcache.enable=1
opcache.memory_consumption=384
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=130986
opcache.validate_timestamps=1
opcache.revalidate_freq=60
opcache.error_log=/var/log/opcache_error.log
extension=imagick.so
Can someone advise on how to solve this problem or where else I should look again?
